Development and evaluation of lysine-crosslinked re-crosslinkable particle gel for water control in high-temperature reservoirs

Preformed particle gel (PPG) treatment is a cost-effective technology for controlling excessive water production. However, PPG exhibits limited plugging efficiency when dealing with open fractures at high temperatures. This paper reports a novel environmentally friendly, high-temperature resistant re-crosslinkable PPG (EF-HT-RPPG). The polymer backbone of EF-HT-RPPG is methylene bisacrylamide crosslinked poly (acrylamide-co N-vinylpyrrolidone). The secondary crosslinker is pre-embedded during the synthesis process, and the hydrated gel particles can reform a bulk gel at high temperatures through chemical re-crosslinking between polymer chains and the secondary crosslinker which is lysine. This study investigated the swelling, re-crosslinking behavior, hydrolytic thermal stability, and plugging performance of the EF-HT-RPPG. Bottle tests were conducted to determine the swelling kinetics, re-crosslinking time, and thermal stability data. The plugging efficiency was assessed using a fracture model. EF-HT-RPPG could re-crosslink at 80 to 130 °C within a reasonable time. The storage modulus (G′) of the re-crosslinked gel with a swelling ratio of 10 was measured at 477 Pa. Additionally, gels prepared in Ekofisk formation water remained stable at 130 °C for over 350 days. The plugging test demonstrated that EF-HT-RPPG could be readily injected into the fracture, with a water breakthrough pressure gradient of 70 psi/ft.